Apparatus for shaping a spiral catalyst support

ABSTRACT

A spiral-wound metal catalyst support is disclosed, wherein the layers of the spiral cannot telescope outwardly in either direction. The support is formed by first winding together a flat strip and a corrugated strip, the strips being wound on a mandrel. The mandrel is removed to leave an axial hole. The catalyst support is then flattened at each end, so as to close the axial hole at each end. The flattening is done in mutually perpendicular directions, so that the catalyst support has tapers in both of two directions. The tapers prevent telescoping of the layers of the support. The catalyst support can be placed in a tube before it is flattened, and then the tube and the support can be flattened together, so that the support becomes firmly anchored in the tube. In an alternative embodiment, a second, tapered mandrel is inserted into the support before flattening, the tapered mandrel having a shape conforming to the inner cavity defined by the flattened support. The support is thereby anchored on the tapered mandrel, further preventing the layers of the support from telescoping. The invention also includes a method of making the catalyst support.

This is a division of application Ser. No. 763,975, filed Aug. 9, 1985,now U.S. Pat. No. 4,598,063, issued July 1, 1986.

BACKGROUND OF THE INVENTION

The present invention relates to the field of catalyst supports,especially for use in catalytic converters for automobiles. The catalystsupport of the present invention is of the type which is known as a"honeycomb", because the support has a cross-section which resembles ahoneycomb. The terms "honeycomb" and "catalyst support" are usedinterchangeably herein.

Catalyst supports having a spiral shape have been known in the priorart. The spiral structure is simple to build, but it has suffered from amajor disadvantage which has limited its use for catalytic converters.This disadvantage is that the spiral supports of the prior art telescopeoutwardly, due to the pulsating exhaust of the automobile.

In Paper No. 850131 of the Society of Automotive Engineers (SAE), theproduction of a metal catalyst support having a "racetrack" crosssection is described. By "racetrack" is meant the shape which isobtained when a circle is divided along a diameter, and the resultingsemicircles are separated by a distance of about one radius, thesemicircles being connected by tangents. This shape is commonly used forcatalytic converters for automobiles. In the cited SAE paper, a flatstrip and a corrugated strip are wound together on a mandrel, and thenthe mandrel is removed. The catalyst support is flattened in a press toconvert the cylindrical cross section into a racetrack. The round holein the center becomes a straight line seam parallel to the flat sides ofthe racetrack.

So far, the only known way to prevent telescoping has been to brazetogether the layers of the spiral over a short length at each end of thespiral. For example, the cited SAE paper states that the layers of thecatalyst support must be brazed to prevent the support from telescoping.While brazing does prevent telescoping, it is expensive, and it alsorestricts the choice of metal for the spiral to those metals that can bebrazed. Such metals are not the best catalyst supports.

The present invention provides a structure which prevents telescoping ofthe layers of a spiral catalyst support. The invention does not requirebrazing of the metal, so that any metal can be used. The invention alsoincludes a method of making a metal spiral-shaped catalyst support.

SUMMARY OF THE INVENTION

The catalyst support of the present invention is formed by first windingtogether a pair of metal strips, one flat and one corrugated.Alternatively, two corrugated strips can be wound together, if thestrips have mutually inclined corrugations, so that the strips cannotnest together. The catalyst support can also be made by winding a singlestrip upon itself when the strip has cylindrical indentations thatmaintain the spacing between the layers. This construction is shown inU.S. Pat. Nos. 4,162,993 and 4,301,039, wherein the strip or strips arewound together on a mandrel, and the mandrel is then removed to leave anaxial hole.

The resulting structure, after being inserted into a cylindrical tube orshell, is flattened at each end, so as to close completely the axialhole at each end, and to provide a continuously tapered catalystsupport. The flattening is done in different directions at the two ends.In the preferred embodiment, the flattening at one end is done in adirection perpendicular to that of the flattening at the other end. Theseams formed by the flattened axial holes are therefore perpendicular toeach other. The tapers in the support insure that the layers of thespiral cannot telescope outwardly in either direction.

In another embodiment, the honeycomb catalyst support can be flattenedat only one end. This flattening also produces tapers in both of twodirections, and also prevents telescoping of the layers of the support.

While it is preferable to flatten the support after it has been insertedinto the tube, it is also possible to fit a preformed tube, havingindentations which conform to the shape of the tapered catalyst support,around the support, after the support has been flattened. With eithermethod of construction, the resulting catalyst support is firmlyanchored in the tube.

In still another embodiment, the support is flattened over a taperedmandrel. The tapered mandrel is shaped to conform substantially to theshape of the cavity defined by the support. The tapered mandrel ispermanently fixed within the final product, thereby firmly anchoring thesupport on the tapered mandrel, and further preventing telescoping ofthe layers.

It is therefore an object of the present invention to provide a spiralwound metal catalyst support which cannot telescope outwardly.

It is another object of the invention to provide a simple solution tothe problem of telescoping in spiral wound catalytic converters forautomobiles.

It is another object of the invention to provide a support as describedabove, wherein the support has two continuous tapers in both of twodirections.

It is another object of the invention to provide a support as describedabove, wherein the support is flattened at only one end.

It is another object of the invention to provide supports as describedabove, wherein the layers of the support do not need to be brazed, andwherein any metal can be used to construct the support.

It is another object of the invention to provide support having theadvantages described above, and wherein the support provides a pluralityof unobstructed channels for gas flow.

It is another object of the invention to provide support which is formedover a mandrel having a shape which generally conforms to the shape ofthe interior cavity of the flattened support.

It is another object to provide an economical method of making aspiral-shaped metal catalyst support which does not telescope outwardly.

Other objects and advantages of the invention will be apparent to thoseskilled in the art, from a reading of the following brief description ofthe drawings, the detailed description of the invention, and theappended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an end view of the metal catalyst support of the presentinvention, the support having been flattened at both ends to form tapersin two directions. The layers of the support are shown in fragmentaryform.

FIG. 2 is an end view of a metal catalyst support before it has beenflattened, also showing the layers in fragmentary form.

FIG. 3 is a perspective view of the catalyst support shown in FIG. 1.

FIG. 4 is an end view of a catalyst support that has been flattened atone end only, and showing the layers of the support in fragmentary form.

FIG. 5A is a side elevational view of the apparatus used in the methodof making the catalyst support of the present invention.

FIG. 5B is an end view of the apparatus shown in FIG. 5A.

FIG. 5C is a side elevational view of the catalyst support.

FIG. 5D is an end view of the catalyst support shown in FIG. 5C.

FIG. 5E is a cross-sectional view taken along the line 5E--5E of FIG.5C.

FIG. 5F is a cross-sectional view taken along the line 5F--5F of FIG.5C.

FIG. 6A is a diagram showing a geometric construction illustrating theshape of the cavity inside the flattened catalyst support.

FIG. 6B is a view taken in the direction of arrow 101 in FIG. 6A,illustrating the hypothetical lines defining the surfaces of the cavityinside the flattened support.

FIG. 6C is a cross sectional view, taken along the line 6C--6C of FIG.6A.

FIG. 7A is a side elevational view of the mandrel used to anchor thecatalyst support of the present invention.

FIG. 7B is a cross sectional view of the mandrel, taken along the line7B--7B of FIG. 7A.

FIGS. 7C and 7D are end view of the mandrel shown in FIG. 7A, taken atthe left hand side and at the right hand side of FIG. 7A, respectively.

FIG. 8 is an end view showing a catalyst support of the presentinvention, inserted within a tube.

DETAILED DESCRIPTION OF THE INVENTION

The catalyst support of the present invention is made by first winding aflat metal strip and a corrugated metal strip to form a spiral-shapedstructure. The strips are wound together on a mandrel, which is removedafter the winding, to leave an axial hole. Alternatively, two corrugatedstrips can be wound together, when the strips have mutually inclinedcorrugations, so that the corrugations do not nest together. Thecatalyst support can also be made by winding a single strip upon itselfwhen the strip has cylindrical indentations that maintain the spacingbetween the layers. This construction is shown in U.S. Pat Nos.4,162,993 and 4,301,039, the disclosures of which are incorporated byreference herein. The resulting structure is illustrated in the end viewof FIG. 2, which shows honeycomb 20 having axial hole 21. Honeycomb 20of FIG. 2 becomes honeycomb 10 of FIG. 1, after being flattened.

FIG. 2 also shows some of the layers of flat and corrugated strips whichdefine the honeycomb. Flat strip 1 and corrugated strip 3 are visible.The layers are shown, in the figures, in fragmentary form only.

The spiral catalyst support of FIG. 2 is to be flattened at both ends.The flattening is done in mutually perpendicular directions, althoughwhat is important is that the flattening be done in directions which arenon-parallel. The resulting support is illustrated in FIG. 1. FIG. 1 isan end view of a honeycomb catalyst support 10 which has been flattenedat both ends. The support 10 has a racetrack cross section at each end,as indicated by racetracks 11 and 12. The axes of the racetracks 11 and12 are at right angles to each other. Seams 13 and 14, on each end ofhoneycomb 10, are formed by the closing off of the axial hole, such asis shown by reference numeral 21 in FIG. 2, during the flatteningprocess. The flat strip 1 and corrugated strip 3 are still visible inFIG. 1. Although the shape of the cross-section has changed, theseparation between adjacent layers is maintained.

The seams 13 and 14 both have a length of (π)/2 times d, where d is thediameter of axial hole 21 of FIG. 2. The long axis of the racetrackcross sections 11 and 12 has a length equal to D+((π/2)-1)d, where D isthe diameter of honeycomb 20. The distance ((π/2)-1)d is just thedifference between one half the circumference of axial hole 21, and thediameter of that hole. The short axes of the racetracks have a lengthequal to D-d. The difference between the long and the short axes isD+((π/2)-1)d-[D-d]=(π/2)d. This is the amount of taper that exists overthe length of the honeycomb, in both of two directions. This is themaximum obtainable taper, and it occurs when the axial hole iscompletely flattened, and when the flattening at one end is done in adirection perpendicular to that of the flattening at the other end.

The perimeter of the racetracks 11 and 12 is equal to the circumferenceof the two semicircles plus the length of the two straight segments 15.The perimeter of the racetracks must also be equal to (π)D, i.e. thecircumference of the original cylindrical honeycomb. If semicircles 16are true semicircles, so that their lengths total 2(π/2) (D-d), thensince the total perimeter is (π)D, the sum of the lengths of thestraight segments 15 must be

    (π)D-2(π/2)(D-d)=2(π/2)d.

This result is just twice the length of seams 13 or 14, and shows thatthe flattened portion of the honeycomb is coextensive with the length ofthe seam.

When the cylinder is flattened to make the racetrack, neither the outerlayer nor any other layer within the spiral has to be stretched. This isa necessary condition because, while a corrugated strip could bestretched slightly, an uncorrugated, flat strip could not be stretchedat all.

The points e₁, e₂, e₃, . . ., e_(g) in FIG. 2 represent arbitrary pointson the edge of cylinder 20. Line segments 17, of FIG. 1, are formed byjoining the corresponding points e_(i) on both edges of the cylinder.The line segments all lie entirely on the surface of the catalystsupport, both before and after the flattening is done. The individualline segments 17 are all straight, but collectively they define thecurved surface indicated in FIG. 1.

FIG. 3 is a perspective view of the catalyst support shown in the endview of FIG. 1. Racetrack 31 is the far face and racetrack 32 is thenear face. Line segments 37 correspond to line segments 17 of FIG. 1.These line segments all lie entirely on the surface of the catalystsupport. The individual line segments 17 and 37 are all straight, butcollectively they define the curved surface indicated in FIGS. 1 and 3.It is important that the line segments be straight lines, because thenthe spacing between the adjacent layers is maintained at every point.All of the channels in the support remain unobstructed after theflattening.

FIG. 4 is an end view of a tapered honeycomb catalyst support 40 that ismade from the same cylindrical structure as that shown in FIG. 2, butwherein only the near end has been flattened. The near face 42 has thesame shape as the racetrack 12 in FIG. 1. The far face 41 is theoriginal circle of FIG. 2. Flat and corrugated strips 1 and 3 are alsovisible, as in FIG. 1. Hole 21 of FIG. 2 survives as round hole 43 inface 41, and as a flat seam which lies along the line BB 44 in face 42.Line AA lies in the far face 41, as seen in FIG. 4, and line BB lies inthe near face. Line AA thus is coincident with the diameter of hole 43,which is equal to d, and line BB is coincident with the flat seam whichhas a length of ((π/2)-1)d. The tapers run in opposite directions, as inFIG. 1. The taper in FIG. 4 is less than that of the support of FIG. 1,so that the support of FIG. 1 givees more positive resistance totelecsoping. Here, again, the elements of the curved surface arestraight lines so that all of the channels remain unobstructed.

When the spiral catalyst support is flattened to form the seams, it ispossible for gas to leak through a slight opening in the seam andthereby bypass the catalyst. This leakage can be prevented by placingsome packing in the axial hole before the flattening is done. Analternative embodiment, discussed below, solves this problem in anotherway, by including a tapered mandrel which occupies substantially all thespace within the interior cavity of the support.

FIGS. 5A, 5B, 5C, 5D, 5E, and 5F show a method and apparatus forflattening a tube or canister that contains a cylindrical catalystsupport. FIG. 5A shows a tube 50 that contains a cylindrical honeycomb51 having an axial hole 52. The diameter of this hole is d, the samedimension indicated for the hole in FIG. 2. Cylindrical mandrels 58 areinserted into both ends of tube 50 to prevent the ends of the tube fromflattening. The flattening is done by plates 53 and 54, there being atotal of four such plates, spaced at 90° intervals around thecircumference of tube 50. This arrangement is shown in the end view ofFIG. 5B. Each plate has a curved lip at one end, indicated by referencenumeral 55 on plates 53. The curved lips on plates 54 are at the endsopposite to the lips on plates 53.

To do the flattening, the curved ends of plates 53 and 54 close togetherby the distance d, the diameter of hole 52. Plates 53 close so as toflatten the honeycomb at the right hand side of FIG. 5A, while plates 54close so as to flatten the honeycomb at the left hand side of the samefigure. The motion of plates 53 is indicated by arrows 56. Thenon-curved ends of plates 53 move apart, by the distance ((π/2)-1)d, asindicated by the arrows 57, due to the simultaneous compression of thehoneycomb by plates 54, at the left hand side of the figure. Similararrows could be drawn, perpendicular to the plane of the drawings, torepresent the movement of plates 54.

In the method described above, both sides of the honeycomb catalystsupport are flattened at once. It is also possible to flatten only oneside at a time. The simultaneous flattenings illustrated in FIG. 5A arepreferable, because of the saving of time of manufacture.

FIG. 5C is a side elevational view, showing the result of the flatteningoperation. The mandrels have been removed, but the ends of tube 50remain circular. Tube 50 has been flattened so that it tapers in both oftwo directions. The taper toward the right terminates in the curvedsurfaces indicated at 70, formed by the curved lips 55 on plates 53. Thetaper toward the left terminates in the curved surface indicated by theshading lines 59, formed by the curved lips on plates 54. The axial hole52 has been flattened into a straight line seam at both ends. The seamis indicated at 60 in the end view of FIG. 5D. Also shown in the endview are the semicircular end of the racetrack 61 formed at the righthand end of the taper, as shown in FIG. 5C, and the semicircular end ofthe racetrack 62 formed at the left hand end of the taper.

FIG. 5E is a cross-sectional view taken along the line 5E--5E of FIG.5C. This section has the shape of racetrack 61. Likewise, FIG. 5F is across-sectional view taken along the line 5F--5F of FIG. 5C, and has theshape of racetrack 62. The flat seam formed by flattening the left handend of hole 52, as shown in FIG. 5C, is indicated by reference numeral63.

The catalyst support shown in FIG. 5C is the finished product. It may beattached to the automobile by joining the circular end portions directlyto the tailpipe, or through the use of a conventional cone or adapterfor matching of diameters.

It is also possible to construct the catalyst support by flattening thewound honeycomb, and then attaching a metal shell which has beenpreviously shaped to conform to the honeycomb. The shell could be formedin two or more pieces, the pieces being welded together when the shellis fitted over the honeycomb. However, the method described above,wherein the honeycomb is first inserted into the cylindrical shell, andwherein the entire structure is flattened at once, is preferable.

When the flattening is done as shown in FIGS. 5A through 5F, the metalof the tube 50 is stretched at the curved surfaces 70 and 59, so thatthe tube and the honeycomb cannot spring back to their original shape.

In FIG. 5A, tube 50 is shown as a straight cylinder. Tube 50 could bereplaced by a canister having ends that taper down to the smallerdiameter of the exhaust pipe. This canister could be formed fromclamshell halves that are clamped around the honeycomb and weldedtogether. The cylindrical mandrels 58 would be replaced by circularclamps around the outside of the canister. The purpose of the clamps isthe same, namely to prevent the ends of the canister from flattening.

An additional feature can be added which more positively preventstelescoping of the layers of the support. When the honeycomb isflattened at each end, a cavity is formed in the core of the honeycomb.Before the honeycomb is flattened, a tapered mandrel is inserted intothe round hole left by the mandrel upon which the honeycomb wasoriginally wound. This tapered mandrel has the shape of the cavity thatwill be formed when the honeycomb is flattened. The tapered mandrelextends beyond the honeycomb at both ends of the honeycomb, and issecured at both ends to tube 50, or to whatever canister is used.

In order to construct the tapered mandrel, it is necessary to understandthe shape of the interior cavity of the flattened catalyst support.FIGS. 6A, 6B, and 6C are idealized geometrical drawings illustrating theshape of the cavity at the core of the flattened catalyst support. Inthese figures, the various directions are labeled as "north", "south","east", and "west" (or N, S, E, and W), for convenience of explanationonly.

In FIG. 6A, circle 100 represents the hole that has been flattened atboth ends. After flattening, the near end of hole 100 forms the flatseam NS, and the far end forms the flat seam EW. The lines NS and EWhave a length equal to π/2 times the diameter of circle 100 (FIG. 6A isthus not drawn entirely to scale). Although the lines NS and EWintersect in the two-dimensional drawing of FIG. 6A, it is apparent thatthese lines lie in distinct, parallel planes.

Points a₁, a₂, . . . a_(g), represent equidistant points along the edgeof the axial hole. For convenience of illustration, only nine suchpoints are shown; eventually, the number of points is allowed toapproach infinity. It is understood that corresponding points a₁, a₂, .. . a_(g) are located on the far end of the axial hole. Now when thehole is compressed at the near end, circle 100 becomes flattened ontothe line NS, and the points a_(i) become superimposed on the points c₁,c₂, . . . c_(g), respectively. Similarly, when the hole is compressed atthe far end, circle 100 is flattened onto the line EW, and the pointsa_(i) become the points b_(i), as shown.

It follows that the shape of the cavity within the compressed catalystsupport can be defined by connecting the corresponding points on thelines NS and EW. Thus, point c₁ is connected to point b₁, point c₂ isconnected to point b₂, etc. The same process is repeated for the otherquadrants, except that there is no need to duplicate lines. Thus, in theexample given, there would be 32 lines drawn. Points d_(i) and f_(i) aretherefore also shown. If the arc length between adjacent points a_(i) isallowed to approach zero, the number of points a_(i) will approachinfinity, and the number of lines drawn will also be infinite. Thisinfinity of lines, in three dimensions, would then define the actualcavity within the catalyst support.

FIG. 6B shows the appearance of the set of lines of FIG. 6A, when viewedfrom the direction indicated by arrow 101. FIG. 6B illustrates the factthat the lines NS and EW are separated from each other by the length ofthe catalyst support. The points b_(i), c_(i), d_(i), and f_(i) areillustrated, except that it is understood that b₁ coincides with d₁, andc₉ coincides with f₉. Lines NS and EW are foreshortened in FIG. 6B by afactor of (1/2) √2, due to the direction from which these lines areviewed. Lines NS and EW do not intersect, but lie in separate, parallelplanes.

In FIG. 6A, a square, defined by the lines connecting the midpoints ofthe semi-axes, (i.e. b₅, c₅, d₅, and f₅) is plainly visible. This squareindicates the cross section of the cavity at the center of the catalystsupport, i.e. at the midpoint along the length of the cavity. If thesupport were flattened into two dimensions, then this square would infact define the actual center of the support. The diagonals of thesquare are parallel to the lines NS and EW. The side of the square isthe distance between arrows M--M of FIG. 6B.

FIG. 6C is a cross-sectional view taken through the cavity, on a planethat includes the line C--C, the plane being perpendicular to the planeof the paper.

The curves 102 and 103 in FIG. 6C can be constructed from FIG. 6A andcan be shown to be parabolas. The construction is as follows. Draw theline indicated by C--C in FIG. 6A. Select one of the previously drawnlines, say c₂ b₂, and let the point of intersection of this line withthe line C--C be called P. The ratio of the distance from c₂ to P, tothe distance from c₂ to b₂, times the distance between the ends of thesupport (i.e. the length of the dotted line in FIG. 6B), is the abscissain FIG. 6C. In FIG. 6C, point P₁ is the origin, and the "horizontal"axis is the line P₁ P₂. Next, measure the distance from the point of(apparent) intersection of the lines NS and EW in FIG. 6A, and point P.This distance is the corresponding ordinate in FIG. 6C.

It can be shown that, if A represents one half the length of the lineNS, the equation of curve 102 in FIG. 6C is

    y=√2Ax(1-x),

with the equation for curve 103 simply being the negative of this curve.The curves 102 and 103 are therefore parabolas. In the above equation, xranges from 0 to 1, the abscissa being in units of the length of thesupport (the length of the dotted line in FIG. 6B). It is important tonote that these curves are symmetric. The maximum difference between theordinates of curves 102 and 103 is indicated by the line M--M, which hasthe length of the square discussed above.

In FIGS. 6A, 6B, and 6C, the shape of the cavity is exaggerated, showinga short and wide cavity. In practice, the cavity would be long and slim.Also, in FIG. 6A, the cavity was assumed to be generated by straightlines. This would require that the layers of metal foil immediatelysurrounding the central hole be compressible along their length and thatthey not bend at all across their length. Actually, the foil can bendsomewhat across the length, despite the corrugations, but a flat stripcannot be compressed along its length without buckling. Therefore theshape generated in FIG. 6A is not meant to be exact. What FIG. 6A doesshow is that both the cavity and the mandrel that fits the cavity have ataper in both of two directions.

If the compression of the ends of the catalyst support is not performedin mutually perpendicular directions, then the shape of the cavity willdeviate from the idealized construction discussed above. In particular,the cross-sectional shape of the cavity, at its center, will not besquare. However, in general, there will be a cavity, and that cavitywill taper towards both ends of the support.

FIG. 7A is a side elevational view of a mandrel 70. The cross section atthe center of the mandrel has a square shape, as shown in FIG. 7B. Thesquare is flattened toward each end along alternate diagonals. Theflattening is complete at points 71 so that there is a completelyflattened length 72 at each end of the mandrel 70. Flat sections 72 areshown again in the end views, FIGS. 7C and 7D. The honeycomb that is tobe flattened upon mandrel 70 will extend beyond the ends of thehoneycomb. When a honeycomb is flattened on mandrel 70, the honeycomband the mandrel are locked together. This is so because the mandrelitself has a taper in both of two directions, and the cavity within thehoneycomb conforms to the mandrel. The mandrel 70 thus remains insidethe final product. In addition to helping to anchor the support andprevent telescoping, the tapered mandrel, by occupying the space withinthe support, also performs the function of the packing materialdiscussed above. When this tapered mandrel is used, the packing materialis not needed.

If the shape of the cavity differs from that discussed above, so thatthe cross-section at its center is not a square, then the taperedmandrel would need to be constructed accordingly. What is important isthat the tapered mandrel conform substantially to the shape of thecavity. It is also important that the honeycomb be flattened so that theflattened seams are aligned with the flattened length 72 on the mandrel.

It is preferred that the tapered mandrel be of tubular construction, toreduce the cost of materials. However, any solid material, capable ofwithstanding the high temperatures present in the catalyst support, canbe used.

FIG. 8 is an end view of a honeycomb within a tube. Tube 80 has beenflattened in both of two directions by the method shown in FIG. 5. Thehoneycomb has been flattened on the mandrel of FIG. 7A, and the mandrelitself has a taper in both of two directions. The flattened end 72extends beyond the honeycomb and is visible in FIG. 8. Cross member 81is welded to flattened end section 72, and also to tube 80. A similarconstruction can exist at the other end of tube 80. Now the honeycomb isanchored in tube 80 by the taper in both of two directions in tube 80and by the taper in both of two directions on mandrel 70.

The objects of the invention are clearly fulfilled by the abovedisclosure. It is understood that the invention can be modified invarious ways, without departing from the spirit of the disclosure. Asstated above, the support which is flattened at two ends may beflattened in directions which are not mutually perpendicular. Theoriginal honeycomb need not be circular. One could start with an ellipseor a racetrack, for example. These and other modifications are to bedeemed within the spirit and scope of the following claims.

What is claimed is:
 1. Apparatus for shaping a honeycomb catalystsupport, the support being contained in a tube, the support including atleast one strip of metal which is spirally wound on a generallycylindrical core to form a cylindrical catalyst support, the support andthe tube having two ends of generally circular shape, the tubeprotruding beyond the ends of the support, the apparatus comprising:(a)two cylindrical mandrels, the cylindrical mandrels both having adiameter which permits the mandrels to be inserted into the ends of thetube, (b) two pairs of plates, the plates being disposed at 90°intervals around the circumference of the tube, and between the ends ofthe tube, the plates being movable towards each other at one end of thetube and away from each other at the other end of the tube, such thatmovement of the plates towards the tube compresses the tube and thecatalyst support contained therein, each plate having a curved lip atone end, and (c) means for moving the plates towards and away from thetube while holding the mandrels within the ends of the tube, wherein themoving means is configured such that the plates of the first pair movetowards each other at the first end of the tube, while the plates of thesecond pair move away from each other at the first end of the tube, andwherein the plates of the second pair move towards each other at thesecond end of the tube, while the plates of the first pair move awayfrom each other at the second end of the tube.
 2. Apparatus for shapinga honeycomb catalyst support, the support being contained in a tube, thesupport including at least one strip of metal which is spirally wound ona generally cylindrical core to form a cylindrical catalyst support, thesupport and the tube having two ends of generally circular shape, thetube protruding beyond at least one end of the support, the apparatuscomprising:(a) at least one cylindrical mandrel, having a diameter whichpermits the mandrel to be inserted into one of the ends of the tube, (b)two pairs of plates, the plates of both pairs being disposed atdiametrically opposite sides of the tube, and between the ends of thetube, the plates being movable towards each other at one end of the tubeand away from each other at the other end of the tube, such thatmovement of the plates towards the tube compresses the tube and thecatalyst support contained therein, and (c) means for moving the platestowards and away from the tube while holding the mandrel in the end ofthe tube, wherein the moving means is configured such that the plates ofthe first pair move towards each other at the first end of the tube,while the plates of the second pair move away from each other at thefirst end of the tube, and wherein the plates of the second pair movetowards each other at the second end of the tube, while the plates ofthe first pair move away from each other at the second end of the tube.3. The apparatus of claim 2, wherein the plates are disposed at 90°intervals around the circumference of the tube.
 4. The apparatus ofclaim 3, wherein there are two cylindrical mandrels, the cylindricalmandrels both being insertable into both ends of the tube.
 5. Theapparatus of claim 4, wherein the plates have a curved lip at one end.6. Apparatus for shaping a honeycomb catalyst support, the support beingcontained in a tube, the support including at least one strip of metalwhich is spirally wound on a generally cylindrical core to form acylindrical catalyst support, the tube and the support having two endsof generally circular shape, the apparatus comprising two pairs ofplates, the plates of both pairs being disposed at diametricallyopposite sides of the tube, and between the ends of the tube, the platesbeing movable towards each other at one end of the tube and away fromeach other at the other end of the tube, such that movement of theplates towards the tube compresses the tube and the catalyst supportcontained therein, and means for moving the plates towards and away fromthe tube, wherein the moving means is configured such that the plates ofthe first pair move towards each other at the first end of the tube,while the plates of the second pair move away from each other at thefirst end of the tube, and wherein the plates of the second pair movetowards each other at the second end of the tube, while the plates ofthe first pair move away from each other at the second end of the tube.7. The apparatus of claim 6, further comprising means for maintainingthe generally circular shape of the ends of the tube while the movingmeans are compressing the tube.